When people suffer from some types of heart arrhythmias, the result may be that blood flow to various parts of the body is reduced. Some arrhythmias may even result in a Sudden Cardiac Arrest (“SCA”). SCA can lead to death very quickly, e.g. within 10 minutes, unless treated in the interim.
Some people have an increased risk of SCA. People at a higher risk include individuals who have had a heart attack, or a prior SCA episode. A frequent recommendation is for these people to receive an Implantable Cardioverter Defibrillator (“ICD”). The ICD is surgically implanted in the chest, and continuously monitors the person's electrocardiogram (“ECG”). If certain types of heart arrhythmias are detected, then the ICD delivers an electric shock through the heart.
After being identified as having an increased risk of an SCA, and before receiving an ICD, these people are sometimes given a wearable cardioverter defibrillator (“WCD”) system. (Earlier versions of such systems were called wearable cardiac defibrillator (“WCD”) systems) A WCD system typically includes a harness, vest, or other garment that the patient is to wear. The WCD system includes a defibrillator and electrodes, coupled to the harness, vest, or other garment. When the patient wears the WCD system, the external electrodes may then make good electrical contact with the patient's skin, and therefore can help determine the patient's ECG. If a shockable heart arrhythmia is detected, then the defibrillator delivers the appropriate electric shock through the patient's body, and thus through the heart.
A problem is that diagnosis for purposes of deciding whether to shock or not is not always perfectly reliable. Measures can be taken to increase the sensitivity of the detection, i.e. the ability of a test to correctly identify cardiac rhythms that require an electric shock. A challenge with increasing sensitivity, however, is that more events could be identified as shockable than actually are shockable. When this happens, the patient wearing the WCD system may be shocked needlessly, which results in discomfort and lack of desire to wear the WCD system.
A partial solution to this problem has been to enlist the patient's help in clearing events that are falsely identified as shockable. For example, some WCD systems emit an alarm warning that an event has been detected, and that an electric shock will be administered soon. Such systems also include a button that the patient may press to prevent the electric shock from being administered. This button is sometimes known as a “live man switch” or an “I am alive” switch. Even having to listen to the alarm and use this button to prevent being shocked, however, is a distraction to the patient.